SELECT * FROM bg_qa where id in (select id from bg_qa where tenant_id=3 and package_id in (0) and status = 1 and category_id in (1574)
union select belong from bg_qa where tenant_id=3 and package_id in (0) and status = 1 and category_id in (1574))
the above statement failed to query
but there is no problem with querying words and sentences separately:
select id from bg_qa where tenant_id=3 and package_id in (0) and status = 1 and category_id in (1574)
union select belong from bg_qa where tenant_id=3 and package_id in (0) and status = 1 and category_id in (1574)
SELECT * FROM bg_qa where id in (123, 321)
the following sentence can be queried. Can you explain why
SELECT * FROM bg_qa where id in (select id from (select id from bg_qa where tenant_id=3 and package_id in (0) and status = 1 and category_id in (1574)
union select belong from bg_qa where tenant_id=3 and package_id in (0) and status = 1 and category_id in (1574)) as abc)